The present invention relates to an overwriting recorder for use in a photomagnetic recording apparatus capable of simultaneously erasing and writing information signals.
There have already been known photomagnetic recording apparatus capable of simultaneously erasing and writing information signals. One of the conventional photomagnetic recording apparatus employs an overwriting system operating on magnetic field modulation. In such an overwriting system, however, it is highly difficult to effect high-speed modulation as it would require an impractically large-size apparatus. Another type of conventional photomagnetic recording apparatus uses two laser beams one for erasing stored information and the other for writing new information. According to the latter arrangement, the optical systems used are complex because of the requirement of the two laser beams and must be synchronized with each other. The apparatus employing two laser beams may not come under the strict definition of "overwriting" since the erasing and writing units are different from each other.